In the wheels and spheres of the great cosmic machine, there are places where spheres will clash with one another. Though both emerge, both are changed by the interaction. Time demonstrates that at some point in the past, most all of the spheres have come in contact with one another. This is why their is land in the elemental plane of air, and seas on the elemental plane of metal.
Excerpt from The Lectures of Gruis the Informed
The Thanatoros Infection is an elemental parasite, not quite fungus, not quite bacteria. Rock that has been contaminated by the infection takes on a milky hue as the outer layers of the stone fragment and break away like dry crumbling skin from the joints of a mummy. The infection has no noticable odor, nor is it harmful to organic life in an of itself. A piece of stone that has become infected begins to rot. This is not the wet and foul smelling rot of organic material, but the crumbling decomposition of the stone into powdery flakes that quickly turn to ooze in the presence of water.
Living stone, or stone that is still connected to the bedrock of the earth is largely immune to the Thanatoros Infection. Cut or worked stone, the sort castles and towers are made of are quite vulnerable on the other hand. In a few weeks, the infection can render foundation stones as weak as termite riddled wood. Stone with imperfections, poor cuts and heavy wear succumb the quickest, while highly polished and excellently cut stone can largely turn away the infection as living stone can.
The most commonly accepted origin of the Thanatoros Infection comes from the diaries of the Wizard Gerlander, a known planes traveler and gem collector. Whilst on one of his sojourns to the elemental plane of earth to collect new specimens for his collection, Gerlander encountered a region of the plane that had recently come in contact with a highly entropic plane. Recently being a relative term, as the encounter was postulated to have been some 1200 years before Gerlander found the site. After examining the site, and the way the stone was corroded, pitted, and falling apart the arch-mage returned to his tower and paid no more though to the event.
Some months later Gerlander was killed when the upper floors of his tower collapsed. When the servants cleaned out his chambers, shaking rugs out of the tower windows, dust contaminated from the site were showered across the face of the tower. The Thanatoros Infection quickly infested the tower, moving through weak points in the stone for weeks without notice. Eventually, one of the support beams became too fragile and cracked under the load of the tower above and the whole works came crashing down. Within a year, little more than iron brackets and broken wood remained of the tower as the infection broke the entire mess down before being rendered harmless by dispersion and rain.
The Thanatoros Infection is spread by small particles of infected rock, generally moved by wind and such. The presence of organic life moves the contagion about very efficiently. This dust remains virulent for about 24 to 48 hours before becoming inert, though certain conditions can extend this period of contagion, though generally not more than a week or so.
Protection and Prevention
Most mages who learn spells specific to the elemental realm of Earth and who are familiar with the way that the Thanatoros Infection functions can generally create a magical seal, or vaccine for stone in an area affected. The spell generally causes the stone in question to behave as if it were living rock, drawing away a small portion of the ambient essence to maintain the facade.